[DevTools] Implement DevToolsManager::Observer which notifies about target updates.

content/browser/devtools/devtools_manager.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_MANAGER_H_
 #define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_MANAGER_H_
 
 #include <map>
+#include <set>
 #include <string>
 #include <vector>
 
+#include "base/cancelable_callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
+#include "base/observer_list.h"
+#include "content/public/browser/devtools_manager_delegate.h"
 
 namespace content {
 
-class DevToolsManagerDelegate;
+class DevToolsAgentHost;
+class RenderViewHost;
+class WebContents;
 
 // This class is a singleton that manage global DevTools state for the whole
 // browser.
 class DevToolsManager {
  public:
+  class Observer {

[pfeldman, 2014/09/22 16:16:50]

This is something in between of listener and observer as per our style.

[dgozman, 2014/09/24 13:18:28]

I've added all empty implementations, and left this as Observer.

+   public:
+    virtual ~Observer() {}
+
+    typedef DevToolsManagerDelegate::TargetList TargetList;
+
+    // Called when any target information changed.
+    virtual void TargetListChanged(const TargetList& targets) = 0;
+  };
+
   // Returns single instance of this class. The instance is destroyed on the
   // browser main loop exit so this method MUST NOT be called after that point.
   static DevToolsManager* GetInstance();
 
   DevToolsManager();
   virtual ~DevToolsManager();
 
   DevToolsManagerDelegate* delegate() const { return delegate_.get(); }
-  void OnClientAttached();
-  void OnClientDetached();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  void RenderViewCreated(WebContents* web_contents, RenderViewHost* rvh);
+  void AgentHostChanged(scoped_refptr<DevToolsAgentHost> agent_host);
+
+  static void SetObserverThrottleIntervalForTest(base::TimeDelta interval);
 
  private:
   friend struct DefaultSingletonTraits<DevToolsManager>;
 
+  void UpdateTargetList();
+  void UpdateTargetListThrottled();
+  void NotifyTargetListChanged(const Observer::TargetList& targets);
+
   scoped_ptr<DevToolsManagerDelegate> delegate_;
-  int client_count_;
+  ObserverList<Observer> observer_list_;
+  std::set<DevToolsAgentHost*> attached_hosts_;
+  bool update_target_list_required_;
+  bool update_target_list_scheduled_;
+  base::CancelableClosure update_target_list_callback_;
+
+  static base::TimeDelta observer_throttle_interval_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_MANAGER_H_